Solar power generation systems for generating solar power in which a plurality of solar cell strings are placed in a matrix on the roof of buildings or the like are beginning to come into wide use. In such solar cells power generation system, each, solar cell module is provided with a terminal box that can make an electrical connection with another solar cell module placed adjacent to the solar cell module.
An example of a conventional terminal box is shown in FIG. 5 as a conventional technique 1. FIG. 5(a) is a cross-sectional view, and FIG. 5(b) is a plan view.
A terminal box 200 according to the conventional technique 1 includes a box case 201 that is placed on and fixed to the back face of the solar cell string 300 in order to electrically connect an output lead wire 301 drawn through a back film 310 of a solar cell string 300 and a terminal panel 210 that is formed on the box case 201. The box case 201 includes a case main body 202 that is placed on and fixed to the back face of the solar cell string 300 and a terminal panel fixing portion 203 for placing and fixing the terminal panel 210 above the case main body 202.
In the case main body 202, a main body through hole 204 for drawing upward the output lead wire 301 drawn from the back face of the solar cell string 300 is formed. One end 211 of the terminal panel 210 facing the main body through hole 204 is provided so as to protrude from the terminal panel fixing portion 203, and a terminal panel through hole 212 for passing a tip 302 of the output lead wire 301 is formed in this protruding portion.
When electrically connecting the output lead wire 301 by using the terminal box 200 configured as described above, firstly, the solar cell string 300 is placed on a workbench (not shown) with its back face facing upward, positioning is performed such that the main body through hole 204 of the terminal box faces the tip 302 of the output lead wire 301 drawn upward from the back face of the solar cell string 300, and the terminal box 200 is placed from above on the solar cell string 300. Next, in this state, the output lead wire 301 protruding upward from the main body through hole 204 is held with tweezers or the like and bent toward the terminal panel 210, and then the tip 302 of the output lead wire 301 is passed through the terminal panel through hole 212 formed in the terminal panel 210 from above. Then, in this state, the output lead wire 301 on the terminal panel 210 is fixed to the terminal panel 210 by soldering, and thereby the output lead wire 301 is attached and fixed to the terminal panel 210.
The reason that the tip 302 of the output lead wire 301 is passed through (latched on) the terminal panel through hole 212 and then fixed by soldering rather than simply fixing the output lead wire by soldering is because it is defined as such by IEC (International Electro Technical Commission) standards which define that simply fixing a wire by soldering will not suffice.
As another example of a conventional terminal box, the structure of a terminal box (connection box) disclosed in Patent Document 1 is shown in FIG. 6.
A terminal box 402 disclosed in Patent Document 1 has a structure in which the tip of a lead frame 416 inserted from a frame insertion hole 426 is connected, by soldering, to the other longitudinal end of a terminal 421 that is inserted from a cable through hole 410 of a box main body 424 and that is latched on a terminal fixing portion 427 so as to not come out, and the lower face of the box main body 424 of the terminal box 402 is adhesively fixed to the back face of a solar cell string main body 401 with an adhesive.
On the other hand, in the terminal box 100 of the conventional technique 1 described above, the output lead wire 201 and the terminal panel 110 are fixed by soldering, but a terminal box configured to eliminate such a soldering step has been proposed (see, for example, Patent Document 2).
As shown in FIG. 7, a terminal box disclosed in Patent Document 2 is attached so as to cover an electrode lead-out portion 506 of a solar cell string 507, and an internal lead wire insertion hole 508 for inserting an internal lead wire 503 is formed in the bottom face of the terminal box 501. Inside the terminal box 501, a relay terminal support 505 for mechanically fixing a relay terminal 504 is formed near the internal lead wire insertion hole 508. The internal lead wire 503 and an external output line 502 are electrically and mechanically connected to each other by the relay terminal 504, and the relay terminal 504 is mechanically fixed to the relay terminal support 505 with the stick-shaped relay terminal support 505 passing through a locking portion (opening) 513 formed in the relay terminal 504.